Add _dbus_counter_notify and call it after every adjustment

When fd-passing is implemented, adjustments happen in pairs; in that case
we coalesce the two calls into one.

Reviewed-by: Colin Walters <walters@verbum.org>
Bug: https://bugs.freedesktop.org/show_bug.cgi?id=34393

dbus/dbus-message.c

@@ -254,6 +254,8 @@ _dbus_message_add_counter_link (DBusMessage  *message,
 #ifdef HAVE_UNIX_FD_PASSING
   _dbus_counter_adjust_unix_fd (link->data, message->unix_fd_counter_delta);
 #endif
+
+  _dbus_counter_notify (link->data);
 }
 
 /**
@@ -313,6 +315,7 @@ _dbus_message_remove_counter (DBusMessage  *message,
   _dbus_counter_adjust_unix_fd (counter, - message->unix_fd_counter_delta);
 #endif
 
+  _dbus_counter_notify (counter);
   _dbus_counter_unref (counter);
 }
 
@@ -575,6 +578,7 @@ free_counter (void *element,
   _dbus_counter_adjust_unix_fd (counter, - message->unix_fd_counter_delta);
 #endif
 
+  _dbus_counter_notify (counter);
   _dbus_counter_unref (counter);
 }
 

dbus/dbus-resources.c

@@ -68,6 +68,7 @@ struct DBusCounter
 
   DBusCounterNotifyFunction notify_function; /**< notify function */
   void *notify_data; /**< data for notify function */
+  dbus_bool_t notify_pending : 1; /**< TRUE if the guard value has been crossed */
 };
 
 /** @} */  /* end of resource limits internals docs */
@@ -105,6 +106,7 @@ _dbus_counter_new (void)
   counter->notify_unix_fd_guard_value = 0;
   counter->notify_function = NULL;
   counter->notify_data = NULL;
+  counter->notify_pending = FALSE;
   
   return counter;
 }
@@ -148,8 +150,9 @@ _dbus_counter_unref (DBusCounter *counter)
 /**
  * Adjusts the value of the size counter by the given
  * delta which may be positive or negative.
- * Calls the notify function from _dbus_counter_set_notify()
- * if that function has been specified.
+ *
+ * This function may be called with locks held. After calling it, when
+ * any relevant locks are no longer held you must call _dbus_counter_notify().
  *
  * @param counter the counter
  * @param delta value to add to the size counter's current value
@@ -177,14 +180,33 @@ _dbus_counter_adjust_size (DBusCounter *counter,
         counter->size_value >= counter->notify_size_guard_value) ||
        (old >= counter->notify_size_guard_value &&
         counter->size_value < counter->notify_size_guard_value)))
-    (* counter->notify_function) (counter, counter->notify_data);
+    counter->notify_pending = TRUE;
+}
+
+/**
+ * Calls the notify function from _dbus_counter_set_notify(),
+ * if that function has been specified and the counter has crossed the
+ * guard value (in either direction) since the last call to this function.
+ *
+ * This function must not be called with locks held, since it can call out
+ * to user code.
+ */
+void
+_dbus_counter_notify (DBusCounter *counter)
+{
+  if (counter->notify_pending)
+    {
+      counter->notify_pending = FALSE;
+      (* counter->notify_function) (counter, counter->notify_data);
+    }
 }
 
 /**
  * Adjusts the value of the unix fd counter by the given
  * delta which may be positive or negative.
- * Calls the notify function from _dbus_counter_set_notify()
- * if that function has been specified.
+ *
+ * This function may be called with locks held. After calling it, when
+ * any relevant locks are no longer held you must call _dbus_counter_notify().
  *
  * @param counter the counter
  * @param delta value to add to the unix fds counter's current value
@@ -212,7 +234,7 @@ _dbus_counter_adjust_unix_fd (DBusCounter *counter,
         counter->unix_fd_value >= counter->notify_unix_fd_guard_value) ||
        (old >= counter->notify_unix_fd_guard_value &&
         counter->unix_fd_value < counter->notify_unix_fd_guard_value)))
-    (* counter->notify_function) (counter, counter->notify_data);
+    counter->notify_pending = TRUE;
 }
 
 /**
@@ -261,6 +283,7 @@ _dbus_counter_set_notify (DBusCounter               *counter,
   counter->notify_unix_fd_guard_value = unix_fd_guard_value;
   counter->notify_function = function;
   counter->notify_data = user_data;
+  counter->notify_pending = FALSE;
 }
 
 #ifdef DBUS_ENABLE_STATS

dbus/dbus-resources.h

@@ -42,6 +42,7 @@ void         _dbus_counter_adjust_size       (DBusCounter *counter,
                                               long         delta);
 void         _dbus_counter_adjust_unix_fd    (DBusCounter *counter,
                                               long         delta);
+void         _dbus_counter_notify            (DBusCounter *counter);
 long         _dbus_counter_get_size_value    (DBusCounter *counter);
 long         _dbus_counter_get_unix_fd_value (DBusCounter *counter);